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"Animals encode a memory of an environment as they run around," said Kemere, an assistant professor of electrical and computer engineering who specializes in neuroscience. "They form a spatial map as individual neurons are activated in different places. When they're awake in our experiments, they're probably doing that exploration process 40 to 60 percent of the time.
"But for the other 40 percent, they're scratching themselves, or they're eating, or they're sort of snoozing," he said. "They're not asleep, but they're paused; I like to call it introspecting."
Those periods of introspection provided the critical data for the study that inverted the usual process of matching brain activity to movement while the animals were active. The primary data was gathered over the course of many experiments under the direction of Diba, an associate professor and leader of the Neural Circuits and Memory Lab at Michigan Medicine.
As the animals explored either back-and-forth tracks or maze-like environments, electrodes in their brains sensed sharp wave-associated bursts of neural activity called population burst events (PBEs). In these events, between 50,000 and 100,000 neurons all fire within 100 milliseconds and send ripples throughout the brain that are not yet fully understood.